monad.rb in prelude-0.0.2

- old
+ new
@@ -4,36 +4,48 @@
 #
 #     http://prelude.rubyforge.org 
 #     
 #     Copyright (C) 2006 APP Design, Inc.
 #
-#     This program is free software; you can redistribute it and/or modify
-#     it under the terms of the GNU General Public License as published by
-#     the Free Software Foundation; either version 2 of the License, or
-#     (at your option) any later version.
+#     This library is free software; you can redistribute it and/or
+#     modify it under the terms of the GNU Lesser General Public
+#     License as published by the Free Software Foundation; either
+#     version 2.1 of the License, or (at your option) any later version.
 #
-#     This program is distributed in the hope that it will be useful,
+#     This library is distributed in the hope that it will be useful,
 #     but WITHOUT ANY WARRANTY; without even the implied warranty of
-#     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#     GNU General Public License for more details.
+#     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#     Lesser General Public License for more details.
 #
-#     You should have received a copy of the GNU General Public License along
-#     with this program; if not, write to the Free Software Foundation, Inc.,
-#     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#     You should have received a copy of the GNU Lesser General Public
+#     License along with this library; if not, write to the Free Software
+#     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #++
 
 module Prelude
 
-  # $Id: monad.rb 2 2006-08-25 00:11:17Z prelude $
+  # $Id: monad.rb 7 2006-09-06 17:03:26Z prelude $
   #
-  # Monad implementation is inspired by the following sources: 
-  #
-  # * article "Late to the Party" posted at http://cwilliams.textdriven.com/pages/monads, I could not detect
-  #   the author's name
-  # * writings by MenTaLguY, see http://moonbase.rydia.net/mental/writings/programming/monads-in-ruby/00introduction.html
-  #
-  class Monad
+  # The Monad is an Array only in an implementation sence of the word
+  class Monad < Array
+
+    def wrap(v)
+      [v]
+    end
+
+    def empty
+      []
+    end
+    
+    def join
+      r = []
+      each {|a| r.push *a}
+      r
+    end
+
     def bind(&block)
-      collect(&block).flatten
+      map(&block).join
     end
+
   end # Monad
+
 end # Prelude